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Water system plays a key role in the coupled human‐nature system, and ancient people's experiences to build a water‐adaptative way of life still shed light on human's pursuit for climate resilience today with their innate traditional ecological wisdom. In this paper, taking the Huai'an‐Yangzhou Section of China's Grand Canal, and particularly its hydraulic engineering system as an example, we show the system's success in addressing the multi‐dimensional challenges in a historical geographical context, as well as its landscape‐shaping power across the entire lower Yellow‐Huai River Basin up until today. Therefore, we argue that the system is not merely a hydraulic engineering project, but a cross‐scale adaptive strategy that has deeply impacted generations of people's way of livelihood with its intrinsic resilient nature. We attribute the success to the advantages brought about by the "distributive hydraulic engineering" approach, which is reflected in the ancient Grand Canal‐management, over the "master‐structure dependent" approach which appears to be the common practice in modern hydraulic engineering. For testing the hypothesis, we build complex system models representing the two approaches with the Qingkou Hydraulic Nexus as an example, and by running long‐term simulation, we evaluate the performance of the two approaches with respect to long‐term resilience. We show from a complex network perspective that the former has significant flexibility advantages, and outperforms the former in multi‐goal fulfillment capacities and long‐term resilience especially under a low‐tech, tight resource constraints condition. We conclude the paper with discussions on the implications of the findings, and argue that though with limitations, the traditional ecological wisdom as reflected in the Grand Canal case, with its holistic approach and flexibility design, still sheds lights on today's large‐scale hydraulic engineering projects that pursue a resilient solution for long‐term adaptive survival for the mankind. [ABSTRACT FROM AUTHOR]

The Yangtze River Basin (YRB), a key biodiversity area and a major economic zone in China, the biodiversity of the area is confronted with severe challenges. In this paper, we analyzed species distribution patterns based on a dataset with 18,538 seed plant species to identify hotspots and evaluate conservation effectiveness and gaps of the YRB. We calculated distribution patterns of species richness with the top 5% richness algorithm and complementarity algorithm, and reconstructed a phylogenetic tree and elucidated spatial phylogenetics. There were 214 hotspot grid cells covering only 6.8% of the study region, but containing 88% seed plant species. Then, we conducted correlation analysis on distribution patterns of different algorithms and species categories, which showed moderate or weak correlations between the top 5% richness algorithm and complementary algorithm. Conservation effectiveness analysis indicated there were 116 hotspot grid cells (accounting for 73.6% of the total species) protected by current conservation networks and there are many conservation gaps remaining. Finally, we used the maximum entropy model (MaxEnt) to predict suitable habitat areas of threatened species under current and future climate scenarios. Prediction analysis results indicated future expansion of suitable habitat to the southeast, and reduction in the central and western portions of the study area. When we considered anthropogenic areas, the suitable habitat was severely decreased, indicating the importance of optimizing the layout of conservation networks and comprehensive biodiversity conservation planning in the YRB. [ABSTRACT FROM AUTHOR]

The Taihu Basin, situated on the south side of the Yangtze delta, is a large flood-prone area that has urbanised rapidly. The risk of flooding is set to increase in future because of continued economic development and the impacts of climate change. Scenario analysis has been adopted to help understand the potential impacts of long-term change on flood risk, including the effects of climate change and socio-economic development, thus providing the basis for the development of sustainable flood risk management strategies. This paper describes the flooding processes in the Taihu Basin and sets out strategic questions that the scenario analysis sought to address. It provides an overview of the assessment framework adopted in the China/ UK scientific cooperation project ' China- UK Scenario Analysis Technology for River Basin Flood Risk Management in the Taihu Basin'. Further details of the component studies carried out as part of the project are given in the associated papers in this special issue. [ABSTRACT FROM AUTHOR]

Risk of climate‐related impacts results from the interaction of climate‐related hazards (including hazardous events and trends) with the vulnerability and exposure of human and natural systems. Despite the commitment of the Paris Agreement, the integrate research on climate change risk combining risk‐causing factors and risk‐bearing bodies, the regional differences in climate impacts are still missing. In this paper we provide a quantitative assessment of hazards and socioeconomic risks of extreme events, risks of risk‐bearing bodies in China under global warming of 1.5 and 2.0 °C based on future climate scenarios, and quantitative evaluation theory for climate change risk. For severe heat waves, hazards might significantly intensify. Affected population under 2.0 °C warming might increase by more than 60% compared to that of 1.5 °C. Hazards of severe droughts and floods might strengthen under Representative Concentration Pathway 8.5 scenario. Economic losses might double between warming levels of 1.5 and 2.0 °C, and the population affected by severe floods might continuously increase. Under the integrate effects of multiple disasters, the regions with high population and economic risks would be concentrated in eastern China. The scope would gradually expand to the west with socioeconomic development and intensification of extreme events. High ecological risks might be concentrated in the southern regions of the Yangtze River Basin, while the ecological risk in northern China would expand. High agriculture yield risks might be distributed mainly in south of the North China Plain, the Sichuan Basin, south of the Yangtze River, and west of Northwest China, and the risk levels might continuously increase. Plain Language Summary.: Based on the climate and socioeconomic scenario data from the Inter‐Sectoral Impact Model Inter‐comparison Project and International Institute for Applied Systems Analysis, risks from climate change were identified under different warming levels, considering socioeconomic damage and ecosystem and food production losses. The relatively developed areas of eastern China exhibit high risks, and the risks show a westward and northward expansion trend. Socioeconomic damage, natural ecosystem, and food production losses would increase with socioeconomic development and intensification of global warming. We believe that a quantitative assessment of climate change risk should integrate climate‐related hazards with the vulnerability and exposure of human and natural systems. These results can provide decision‐making support for governments and a database for adapting to climate change. Key Points: Risks of socioeconomic development, ecosystem and food production would increase between 1.5 °C and 2.0 °C warming, economic losses might doubleIncreases in annual socioeconomic losses of 2.0 °C warming would be more significant than those of 1.5 °CEastern China exhibits high integrate risks of climate change, which present westward and northward trends from 1.5 °C to 2.0 °C warming [ABSTRACT FROM AUTHOR]

Acquiring freshwater resources is a necessary component of sustainable human settlement subject to increasing pressure from population and climate changes. This sometimes scarce resource primarily comes from rivers, and international river basins ( IRBs), where watersheds and watercourses cross political boundaries, are often spaces of great political tension and conflict worldwide. Such conflict potential has garnered interest from a wide range of research communities, and each emphasises public access to hydrologic data as integral to successful international management of IRBs. However; these hydrologic data, especially measurements of river flow rate, are often closely guarded state secrets. Satellites have been cited as a key technology set to challenge this data monopoly that have yet been unable to calculate river flow rate without some form of guarded ancillary data. Now, at-many-stations hydraulic geometry ( AMHG) offers a means of circumventing data limitations without any a priori information, and the forthcoming NASA/ CNES Surface Water and Ocean Topography ( SWOT) satellite also promises to estimate flow rates solely from its novel measurements following launch. In this paper, we explore how these newly available estimates of river flow rate could reconfigure water-management and interstate relations in IRBs, and demonstrate AMHG, for two cases: the Ganges- Brahmaputra and Mekong. For these basins we find that satellite flow rate retrievals will likely reinforce and favour state-level negotiations of water resource governance. Also, satellite flow retrievals can have the direct, concrete effect of improving hydrologic understanding of the upstream Ganges- Brahmaputra, a sorely needed advance that will positively benefit millions of Bangladeshis and affect state-level interactions between India, China, and Bangladesh. Finally, we avoid offering prescriptive water management solutions for each case, as local stakeholders will ultimately determine if and how such satellite retrievals will be used. [ABSTRACT FROM AUTHOR]

ABSTRACT The arid region in northwestern China covers 2·02 million square kilometres and is one of the most arid regions in the world. Positioned at the central part of the Eurasian Continent, this region experiences little influence from the Eastern and Southern Asian Monsoons and precipitation is formed mostly from westerly vapour. With a hyper arid climate, the annual precipitation in this region ranges from less than 20 mm at the oasis area to around 600 mm in the mountain regions, whereas potential evaporation can amount to 2000-3000 mm per annum. It is reported that strong evapotranspiration characterizes and dominates the water cycle in the arid basins. Nearly all the water resources of the oasis, where the human society exists, come from the mountain areas as river discharge from glacier/snow melting water, rainfall and subsurface flow from bedrock cracks. As a result, the hydrographs of the arid basins are affected by climate change via changes in precipitation partitioning (the ratio of rainfall and snowfall) and changes to seasonal distributions of precipitation and air temperature. These changes in turn directly affect the water yield and the vegetation response. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Changes in precipitation can be expected to have a major influence on the frequency and severity of flooding in the Taihu Basin. As part of an integrated assessment of flood risk in the Taihu Basin, this paper addresses the hydrological conditions and the potential impacts of climate change on Taihu Lake water levels. The hydrological system is simulated by using the distributed hydrological model VIC ( Variable Infiltration Capacity), with future climate scenarios generated by the regional climate model PRECIS (Providing Regional Climates for Impacts Studies). The results indicate that maximum and mean flood water levels under the A2 and B2 scenarios for 2021-2050 will be higher than the levels during the baseline period (1961-1990), with larger increases under the B2 scenario than for the A2 scenario. The storm return periods leading to extreme water levels in the Taihu Lake in the future is projected to decrease significantly in comparison to the baseline period, implying the potential for the more frequent occurrence of major floods. These results indicate the importance of planning for future flood control in the Taihu Basin. [ABSTRACT FROM AUTHOR]

A geographic information system (GIS)-based analysis tool, the Taihu Basin Risk Assessment System ( TBRAS), is developed to perform scenario analysis of future flood risk changes in the Taihu Basin. The TBRAS integrates modules of climate modelling, hydrological and hydraulic modelling, dyke reliability analysis, socioeconomic analysis, and damage assessment. The results indicate that the TBRAS can provide a broad-scale simulation of the flooding processes and damage evaluation for the entire Taihu Basin. Future climate change by 2050 in precipitation alone can approximately result in four or five times of risk increase compared with the 2005 baseline risk. Socioeconomic changes alone can increase flood risk by four to six times. The paper reveals that, without any proactive responses, the combination of socioeconomic change, sea-level rise, and other climate changes can substantially increase the overall flood risks to 15-37 times of the present situation. We therefore conclude that both structural and non-structural measures for reducing flood risks are required and provide a set of response options for managing and adapting future flood risk changes. [ABSTRACT FROM AUTHOR]

The Tarim River, the largest inland river in China, sits in the Tarim River Basin (TRB), which is an arid area with the ecosystem primarily sustained by water from melting snow and glaciers in the headstream area. To evaluate the pressures of natural disasters in this climate‐change‐sensitive basin, this study projected flash droughts in the headstream area of the TRB. We used the variable infiltration capacity (VIC) model to describe the hydrological processes of the study area, Markov chain Monte Carlo to quantify the parameter uncertainty of the VIC model. Ten downscaled general circulation models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) were used to drive the VIC model, and the standardized evaporative stress ratio was applied to identify flash droughts. The results demonstrated that the VIC model after Bayesian parameters uncertainty analysis can efficiently describe the hydrological processes of the study area. In the future (2021–2100), compared with the plain region, the alpine region has higher flash drought frequency and intensity. Compared with the historical period (1961–2014), the frequency, duration, and intensity of flash droughts tend to increase throughout the study area, especially for the alpine area. Moreover, based on variance decomposition, CMIP6 model is the most important uncertainty source for flash drought projection, followed by the shared socioeconomic pathway of climate change scenario and VIC model parameters. Plain Language Summary: The Tarim River is the largest inland river in China, which is an arid area with the ecosystem primarily sustained by water from melting snow and glaciers in the headstream area. Compared with long‐duration drought, flash drought is more difficult to forecast and identify. We used the variable infiltration capacity model to build a hydrological model of the headstream area of the Tarim River Basin, and the model output (ET data) was used to identify flash droughts. Based on 10 representative Coupled Model Intercomparison Project Phase 6 (CMIP6) models, this study projected the future flash droughts in the study area under climate change. The findings indicated that the alpine region is likely to experience a greater frequency and intensity of flash droughts in the future (2021–2100) compared to the plain region. Compared with the historical period (1961–2014), the frequency, duration, and intensity of flash droughts tend to increase throughout the study area, especially for the alpine area. In addition, the result of uncertainty decomposition revealed that the CMIP6 model is the most important uncertainty source for flash drought projection. Key Points: The hydrological processes of study area are well described by the variable infiltration capacity model and Bayesian uncertainty analysisCompared with the plain region, the alpine region has higher flash drought frequency and intensity in the futureThe Coupled Model Intercomparison Project Phase 6 model is the most important uncertainty source for flash drought projection [ABSTRACT FROM AUTHOR]

Pressure on river water resources may increase continuously under global climate change and the increasing intensity of human activity, and the identification of river water sources is needed to maintain water resource sustainability. In this study, river water sources were studied using hydrochemical tracers (i.e. the major ions) and end‐member mixing analysis (EMMA) during two hydrological years, in the subtropical monsoon basin of the Xiangjiang River in the south‐central China. Various water types including precipitation, river water, and mountain creek water, were collected in the basin at a high frequency. The results of EMMA showed that the average contributions from the direct input of precipitation, near‐surface runoff (represented by mountain creek water), and groundwater (represented by river water sampled during the base flow period) were 28 ± 24%, 49 ± 24% and 23 ± 16%, respectively. The contributions from these water sources to the river water varied greatly within the year, which may indicate a shift in the major flow pathways from direct precipitation input and near‐surface flow pathways in the spring rainy months (e.g. from March to May), to a deeper flow pathway in the dry or rainless months (e.g. January, February, July and December). The shift of the major flow pathways may be due to the factors such as the seasonality of precipitation, evapotranspiration and soil wetness conditions. Groundwater and near‐subsurface runoff dominated the river water and the direct input of precipitation was negligible during the dry or rainless months, and consequently, the river water chemistry was less diluted and more influenced by water‐soil/rock interactions and anthropogenic pollution during these months. The creek water contribution to the river water was relatively high in summer, especially in June and July 2021, which may indicate the substantial inter‐seasonal carryover of precipitation that contributed to the river water. With the projected increased frequency of extreme weather events such as seasonal drought, streamflow in the subtropical monsoon regions may experience greater recharge by deeper flow pathways, with the enhanced role of base flow in regulating streamflow, and there may be an increased risk to the water resource security under the condition of the decreased river dilution capacity and increased anthropogenic pollution. [ABSTRACT FROM AUTHOR]

Climate change and anthropogenic factors have significantly impacted hydrological regimes, especially in semiarid regions. Using the trend‐free pre‐whitening Mann–Kendall (TFPW‐MK) test and linear regression, trends of precipitation, temperature, runoff, and water balances from different spatiotemporal scales were analysed during the past sixty years in the Upper Yongding River Basin (UYRB). Based on the Choudhury‐Yang equation, the contributions of climate change and human activities to runoff variation were further quantified in five mountainous catchments, and the actual effects of climate change and human activities on the water balance in the whole UYRB were also discussed. The results suggest that the UYRB has become much warmer and drier. The lower annual precipitation and intensity in summer were directly attributed to runoff reductions. Intra‐annual scale analyses of meteorological, hydrological and biological responses helped the comprehensive interpretation of the runoff trends. Human activities, including agricultural irrigation, were the main causes for runoff reduction, especially in the middle and lower reaches, and the contribution of human activities increased gradually in recent decades. The water balance changed drastically temporally, with the precipitation being converted less to runoff and more to evaporated fractions, which was also due to the second order effects of climate change and vegetation improvement. It is suggested that low water‐consumption plant species and the related water‐saving techniques in agriculture and afforestation should be introduced for the sustainable development in the similar regions. [ABSTRACT FROM AUTHOR]

Water resources systems in arid regions are sensitive to climate change, which critically impacts the water cycle. In this study, we applied historical hydrometeorological data, CMIP5 data, and a large‐scale hydrological model (Community Land Model–Distributed Time‐Variant Gain Model [CLM–DTVGM]) to study the impact of climate change on the hydrological cycle (i.e., runoff, actual evapotranspiration (ETa), and terrestrial water storage [TWS]) under different scenarios at the Aksu River basin (ARB) located in the arid region of northwest China. The primary findings of this study: (a) As the determination coefficient (R2) and Nash–Sutcliffe efficiency coefficient (NSE) reached desirable levels (R2 ≥ 0.583, NSE ≥ 0.371, and root‐mean‐square error ≤ 155.727), the CLM–DTVGM achieved a better simulation of runoff in the ARB; under climate change, the runoff depth in the irrigation area became shallower and followed a decreasing trend, with a minimum depth of 0.5 mm and a significant decreasing trend of −8 mm·a−1. (b) Along with changes in the precipitation and temperature of the baseline period (i.e., 1980–2010), runoff, ETa, and TWS were predicted to change significantly in future scenarios. (c) Climate change significantly impacted the historical runoff from the Shaliguilanke and Xiehela hydrological stations, with correlation coefficients larger than 0.9; however, the runoff from the Alaer hydrological station was not affected. However, runoff, ETa, and TWS in the ARB were very closely correlated with climate change in the future scenarios, with correlation coefficients exceeding 0.9. Related research in the future would be important for guiding the sustainable development of the ARB. [ABSTRACT FROM AUTHOR]

Afforestation to control soil erosion has been implemented throughout China over the past few decades. The long‐term hydrological effects, such as total water yield and baseflow, of this large‐scale anthropogenic activity remain unclear. Using six decades of hydrologic observations and remote sensing data, we explore the hydrological responses to forest expansion in four basins with contrasting climates across China. No significant change in runoff was found for the period 1970–2012 for the cold and dry Hailar River Basin in northeastern China. However, both forest expansion and reduced precipitation contributed to the runoff reduction after afforestation since the late 1990s. Similarly, afforestation and drying climate since the mid‐1990s induced a significant decrease in runoff for the Weihe River Basin in semi‐arid northwestern China. In contrast, the two wet basins in the humid southern China, Ganjiang River Basin and Dongjiang River Basin, showed insignificant changes in total runoff during their study periods. However, the baseflow in the winter dry seasons in these two watersheds significantly increased since the 1950s. Our results highlight the long‐term variable effects of forest expansion and local climatic variability on basin hydrology in different climatic regions. This study suggests that landuse change in the humid study watersheds did not cause dramatic change in river flow and that region‐specific afforestation policy should be considered to deal with forestation‐water quantity trade‐off. Conclusions from this study can help improve decision‐making for ecological restoration policies and water resource management in China and other countries where intensive afforestation efforts are taking place. Key Points: Both precipitation and afforestation explained reduction in runoff for dry basinsForest recovery did not result in significant changes in total runoff for two wet basinsDry season baseflow in two wet basins had an upward trend [ABSTRACT FROM AUTHOR]

Hydropower dams are proliferating in the riparian countries of the Lancang‐Mekong River Basin (LMRB) driven by the pursuit of renewable electricity and societal resilience to flooding. However, the tradeoffs between hydropower production and flood control are unclear in a changing environment. Here, we use a hydrological variable infiltration capacity model combined with a reservoir module to quantify the relative effects of climate change and reservoir operation on flood and hydropower generation in LMRB. Results show that while climate change would increase flood magnitude and frequency, adaptive reservoir operation can reduce flood magnitude by 5.6%–6.4% and frequency by 17.1%–18.9% at the cost of 9.8%–14.4% of basin‐wide hydropower generation. Particularly, upstream reservoirs suffer more hydropower loss (5.4 times) than downstream ones when flood control is prioritized in reservoir regulation. Our findings have implications for integrated water and energy management at the transboundary river basin under climate change. Plain Language Summary: Dams and reservoirs provide two important services, i.e., flood control and hydropower generation. In this study, we seek to understand the future tradeoff between these two services provided by reservoir regulation in the transboundary Lancang‐Mekong River Basin. Using a modeling based approach, we find that climate change will likely lead to more frequent and larger flood events, but reservoir operation, by regulating water discharges and levels in streams, can effectively reduce flood frequency and magnitude at the expense of hydropower generation. Our results highlight the importance of coordinating water and energy management across countries in this transboundary river basin. Key Points: Reservoir can mitigate future flood risk from climate change at the cost of reducing hydropower generation in the Lancang‐Mekong River BasinReservoir regulation can delay the timing when flood risk exceeds the historical baseline by at least 20 years in Laos and ThailandFlood control measures would reduce hydropower at a magnitude of 5.4 times in China than downstream countries [ABSTRACT FROM AUTHOR]

Climate change has affected the dynamics of the water cycle and its consequent effects on water resources in many regions. The Buyuan River, the largest tributary of the Upper Mekong River, is one of the regions with the strongest climate change in the Mekong River Basin, and its cross‐border impact on water resources has received increasing attention. However, few studies have focused on the runoff responses to future climate change in the Buyuan River Basin (BRB). In this study, the MIKE SHE model was applied to estimate the runoff of the BRB, based on climate‐change scenarios from the Beijing Climate Center Climate System Model (BCC‐CSM1‐1) under two Representative Concentration Pathways (RCPs). The simulations predicted a slight decrease in the mean annual runoff of the BRB under the RCP4.5 and RCP8.5 scenarios (2020–2049) compared with the reference period (1959–2012), with an increase in the magnitude of inter‐annual variation, leading to increased deficit and surplus during dry and wet years. The simulations predicted the earlier maximum monthly runoff and a more evenly distributed annual distribution of the runoff under RCP4.5 and RCP8.5 scenarios as compared to the reference period. The arrival of the flood season in the BRB was advanced by a month under future climate‐change scenarios. The results showed that the average annual runoff of the BRB does not change significantly under future climate‐change scenarios. However, there are obvious changes in the inter‐annual and intra‐annual distribution of the runoff. [ABSTRACT FROM AUTHOR]

Reference evapotranspiration (ETo) is one of the most important factors influencing hydrologic and climatic quantities, and increases in ETo are often considered as a primary cause for drying under global warming scenarios. Based on bias‐corrected data from the Half a degree Additional Warming, Prognosis and Projected Impacts (HAPPI) experiment, we investigated changes in ETo and drying across the Yellow River Basin (YRB) for 1.5°C and 2°C stabilized warming, relative to the current decade (2006–2015). We used changes in the climatic water deficit (WD: defined as precipitation (P) minus (ETo) to determine drying and wetting trends. Results projected that mean annual ETo would increase significantly over the whole YRB, under 1.5°C and 2°C warming scenarios, with an increase of 4.54% (1.57–7.59% full uncertainty range) and 7.66% (4.49–10.61%), at 1.5°C and 2°C, respectively, averaged over the YRB for the multi‐model mean. It is unclear whether the YRB source region (the NE region of the Tibet Plateau) would be drier or wetter under 1.5°C and 2°C of warming, although it is likely that the N regions of the YRB, and the whole YRB except for the source region will be drier under 1.5°C and 2°C warming scenarios, respectively. With an additional 0.5°C warming, further intensification of drying is projected in the whole YRB, resulting from a more pronounced increase in ETo, and lesser increase/decrease in P. The increased ETo projected under a 0.5°C additional warming was mainly attributed to rising maximum temperatures (tasmax). These results highlight the importance of ETo, in terms of potential future YRB drying, and our study suggests that limiting future warming to 1.5°C would impact regional drying the least. [ABSTRACT FROM AUTHOR]

The Earth's climate had undergone a global transition around 4–3 Ma, from warm to cool. The western Wei River Basin, its late Cenozoic tectonic evolution was mainly controlled by the expansion of the Tibetan Plateau, is affected by both Monsoon climate and Westerlies circulation. A set of lacustrine sediments between 4.2 and 3.6 Ma with clearly sedimentary rhythm are good materials for studying the palaeoclimate/palaeoenvironment changes and exploring the contained tectonic implications. We present a high‐resolution grain‐sized, magnetic susceptible, and carbonate content records from the palaeolake sediments at the global climate transition interval (4.2–3.6 Ma) in the western Wei River Basin. The abrupt changes of climate indicators at about 4.14–4.16 Ma, which is a regional response to global cooling, indicate that both westerly and monsoonal circulations were enhanced and should be attributed to global cooling rather than the uplift of TibetanPlateau. From 4.14 to 3.6 Ma, the climate represented stepwise strengthening or weakening with frequent fluctuations on the millennium scale and extreme dry events at 3.77–3.80 Ma. Combined with regional geological environment and palaeoclimate evolution data, the palaeolake that rapidly receded at 3.6 Ma provides evidence for the understanding the major climatic and environmental changes produced by the uplift of the Tibetan Plateau in western Wei River Basin and surrounding areas. [ABSTRACT FROM AUTHOR]

The selection of general circulation models (GCMs) with high capability to represent the past and likely future climate for a specific geographical location is a crucial step to assess impacts of climate change on different sectors. This study included pool of 105 and 78 GCMs for representative concentration pathways (RCPs) 4.5 and 8.5, respectively, from Coupled Model Intercomparison Project—Phase 5, applied an advanced envelope‐based selection approach to select representative GCMs for the Koshi river basin in China and Nepal at short‐term (2016–2045), mid‐century (2036–2065) and end‐of‐century (2071–2100) periods, and developed range of possible future precipitation and temperature scenarios with high resolution downscaled data (10 × 10 km2), which is the novelty contribution of the study. Considering RCP4.5, average annual precipitation is expected to increase by 0–16%, 4–23% and 4–24% in the short‐term, mid‐century and end‐of‐century periods, respectively. Using RCP8.5, equivalent predictions are 6–20%, 6–36% and 13–49% in the short‐term, mid‐century and end‐of‐century periods, respectively. Average annual temperature is expected to increase, but with higher increases during winter than in the monsoon period. Considering RCP4.5, average annual temperature is expected to increase by 1–1.4°C, 1.3–1.9°C and 1.6–2.8°C in the short‐term, mid‐century and end‐of‐century periods, respectively. Similarly, using RCP8.5, equivalent predictions are 1–1.6°C, 1.8–2.9°C and 3.1–5.6°C in the short‐term, mid‐century and end‐of‐century periods, respectively. The ensemble mean of absolute change in average precipitation and temperature projects that High Himalaya and Tibet regions are more sensitive to climate change considering precipitation and temperature, respectively. The results also suggest that GCMs selection for a catchment varies with climate scenarios and specific future time periods. [ABSTRACT FROM AUTHOR]

Glacial retreat and the thawing of permafrost due to climate warming have altered the hydrological cycle in cryospheric‐dominated watersheds. In this study, we analysed the impacts of climate change on the water budget for the upstream of the Shule River Basin on the northeast Tibetan Plateau. The results showed that temperature and precipitation increased significantly during 1957–2010 in the study area. The hydrological cycle in the study area has intensified and accelerated under recent climate change. The average increasing rate of discharge in the upstream of the Shule River Basin was 7.9 × 106 m3/year during 1957–2010. As the mean annual glacier mass balance lost −62.4 mm/year, the impact of glacier discharge on river flow has increased, especially after the 2000s. The contribution of glacier melt to discharge was approximately 187.99 × 108 m3 or 33.4% of the total discharge over the study period. The results suggested that the impact of warming overcome the effect of precipitation increase on run‐off increase during the study period. The evapotranspiration (ET) increased during 1957–2010 with a rate of 13.4 mm/10 years. On the basis of water balance and the Gravity Recovery and Climate Experiment and the Global Land Data Assimilation System data, the total water storage change showed a decreasing trend, whereas groundwater increased dramatically after 2006. As permafrost has degraded under climate warming, surface water can infiltrate deep into the ground, thus changing both the watershed storage and the mechanisms of discharge generation. Both the change in terrestrial water storage and changes in groundwater have had a strong control on surface discharge in the upstream of the Shule River Basin. Future trends in run‐off are forecasted based on climate scenarios. It is suggested that the impact of warming will overcome the effect of precipitation increase on run‐off in the study area. Further studies such as this will improve understanding of water balance in cold high‐elevation regions. [ABSTRACT FROM AUTHOR]

Climate change and human activities are two major driving forces affecting the hydrologic cycle, which further influence the stationarity of the hydrologic regime. Hydrological drought is a substantial negative deviation from the normal hydrologic conditions affected by these two phenomena. In this study, we propose a framework for quantifying the effects of climate change and human activities on hydrological drought. First, trend analysis and change‐point test are performed to determine variations of hydrological variables. After that, the fixed runoff threshold level method (TLM) and the standardized runoff index (SRI) are used to verify whether the traditional assessment methods for hydrological drought are applicable in a changing environment. Finally, two improved drought assessment methods, the variable TLM and the SRI based on parameter transplantation are employed to quantify the impacts of climate change and human activities on hydrological drought based on the reconstructed natural runoff series obtained using the variable infiltration capacity hydrologic model. The results of a case study on the typical semiarid Laohahe basin in North China show that the stationarity of the hydrological processes in the basin is destroyed by human activities (an obvious change‐point for runoff series is identified in 1979). The traditional hydrological drought assessment methods can no longer be applied to the period of 1980–2015. In contrast, the proposed separation framework is able to quantify the contributions of climate change and human activities to hydrological drought during the above period. Their ranges of contributions to hydrological drought calculated by the variable TLM method are 20.6–41.2% and 58.8–79.4%, and the results determined by the SRI based on parameter transplantation method are 15.3–45.3% and 54.7–84.7%, respectively. It is concluded that human activities have a dominant effect on hydrological drought in the study region. The novelty of the study is twofold. First, the proposed method is demonstrated to be efficient in quantifying the effects of climate change and human activities on hydrological drought. Second, the findings of this study can be used for hydrological drought assessment and water resource management in water‐stressed regions under nonstationary conditions. [ABSTRACT FROM AUTHOR]

Baseflow availability and its contribution to streamflow are critical for planning and management of catchment hydrology and ecology. This study uses a digital filtering technique, statistical methods, and hydrological projection to investigate historical and future baseflow characteristics with respect to climate and land use impacts, exemplified by the large Poyang Lake catchment (China). Digital filtering results show that annual baseflow varied between 25 × 108 and 820 × 108 m3/year for the catchment rivers during 1953–2014. The results reveal that on average 62% of the long‐term streamflow in the catchment is derived from baseflow contribution. Statistics show a generally increasing trend in the annual baseflow and baseflow index (BFI) for most of the rivers over the past 60 years, with the major frequencies varying between 5 and 20 years. Although the trends in baseflow and BFI are attributable to the combined effects of climate and land use change across the catchment, baseflow variations are expected to be more sensitive to climate than land use changes. In general, precipitation plays a dominant role in controlling baseflow and can be used as an indication of the variations in baseflow at the subcatchment scale. Hydrological projection shows that annual baseflow and BFI are likely to increase by up to 31% and 13% during 2018–2035, respectively, based on historical baseflow trends. Our results indicate that management approaches for the catchment that consider groundwater and surface water as a joint resource will be needed to effectively manage the current and future river regime, its water resources, and water quality. [ABSTRACT FROM AUTHOR]

Understanding the dominant causes of streamflow alteration and effects of the current water diversion scheme is beneficial for sustainable management of water resources in an arid area. This study presents a quantitative attribution of the run‐off changes between headstreams and mainstream from 1960 to 2015 using the Choudhury–Yang equation and evaluates the effects of 18 times of ecological water conveyance in the lower reaches of the Tarim River Basin (TRB). Our results suggest that climate change was the primary determinant of increase of the streamflow in the headstreams from 2000 to 2015. While in the mainstream, human activities played a dominant role in deduction in the streamflow with the contribution of 54.8–355.6%. Eighteen episodes of ecological water conveyance have a positive effect on rising groundwater level and are highly related to seed falling time of Shrub and Perennial herbaceous and Annual herbaceous except for Arbor. It indicates that restoring the long‐term drying of the lower reaches through continuous water conveyance is feasible, although the existing programme has not restored the entire riparian system. Our study suggests that it is necessary to adopt an integrated approach for water resources allocation rather than relying on a single tributary contribution in the TRB. [ABSTRACT FROM AUTHOR]

Climate and land-use changes could strongly affect wind erosion and in turn cause a series of environmental problems. Thus, the objective of this study was to assess potential wind erosion rate (PWER) response to climate and land-use changes in the watershed of the Ningxia-Inner Mongolia Reach of the Yellow River (NIMRYR), China. The watershed of NIMRYR suffers from serious wind erosion hazards, and over recent decades, wind erosion intensity and distribution has changed, following climate and land-use changes. To understand these processes in the NIMRYR watershed, the Integrated Wind Erosion Modelling System (IWEMS) and the Revised Wind Erosion Equation (RWEQ) were used to calculate the PWER under different climate conditions and land-use scenarios, and to assess the influences of climate and land-use changes on the PWER. The results show the PWER in the whole watershed had a significant declining trend from 1986 to 2013. The results of the relationship among PWER, climate change, and land-use changes showed that climate change was the dominant control on the PWER change in this watershed. Compared to the period 1986-1995, the average PWER decreased 23.32% and 64.98% as a result of climate change in the periods 1996-2005 and 2006-2013, respectively. In contrast with climate change, the effects of land-use changes on the average PWER were much lower, and represented a change in PWER of less than 3.3% across the whole watershed. The study method we used could provide some valuable reference for wind erosion modelling, and the research results should help climate and land-use researchers to develop strategies to reduce wind erosion. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Restored annual streamflow ( Qr) and measured daily streamflow of the Chaohe watershed located in northern China and associated long-term climate and land use/cover data were used to explore the effects of land use/cover change and climate variability on the streamflow during 1961-2009. There were no significant changes in annual precipitation ( P) and potential evapotranspiration, whereas Qr decreased significantly by 0.81 mm/yr ( p < 0.001) over the study period with a change point in 1999. We used 1961-1998 as the baseline period ( BP) and 1999-2009 the change period ( CP). The mean Qr during the CP decreased by 39.4 mm compared with that in the BP. From 1979 to 2009, the grassland area declined by 69.6%, and the forest and shrublands increased by 105.4 and 73.1%, respectively. The land use/cover change and climate variability contributed for 58.4 and 41.6% reduction in mean annual Qr, respectively. Compared with the BP, median and high flows in the CP decreased by 38.8 and up to 75.5%, respectively. The study concludes that large-scale ecological restoration and watershed management in northern China has greatly decreased water yield and reduced high flows due to the improved land cover by afforestation leading to higher water loss through evapotranspiration. At a large watershed scale, land use/cover change could play as much of an important role as climate variability on water resources. [ABSTRACT FROM AUTHOR]

Ji, Yuhe, Liding Chen, and Ranhao Sun, 2012. Temporal and Spatial Variability of Water Supply Stress in the Haihe River Basin, Northern China. Journal of the American Water Resources Association (JAWRA) 48(5): 999-1007. DOI: 10.1111/j.1752-1688.2012.00671.x Abstract: Water resources are becoming increasingly stressed under the influence of climate change and population growth in the Haihe River Basin, Northern China. Assessing the temporal and spatial variability of water supply stress is urgently needed to mitigate water crisis caused by water resource reallocation. Water supply and use data were compiled for the time period of 1998-2003 in this synthesis study. The Water Supply Stress Index (WSSI) as defined as Water Demand/Water Supply was used to quantitate whether water supply could meet the demand of human activities across the study region. We found a large spatial gradient of water supply stress in the study region, being much higher in the eastern subbasins (ranging from 2.56 to 4.31) than the west subbasins (ranging from 0.56 to 1.92). The eastern plain region not only suffered more serious water supply stress but also had a much higher interannual variability than the western hilly region. The uneven spatial distribution of water supply stress might result from the distribution of land use, population, and climate. Future climate change and rapid economic development are likely to aggravate the existing water crisis in the study region. [ABSTRACT FROM AUTHOR]

The article discusses a study on the effect of land use/cover change (LUCC) on Lake Qinghai Watershed on the northeastern margin of the Qinghai-Tibet Plateau. Noted is the vulnerability and sensitivity of the lake's ecosystem to climate change and human interference. Through the use of geographical information system (GIS) and remote sensing (RS), the researchers were able to analyze LUCC pattern in the watershed between 1977 and 2004. Based on the analysis, the watershed is dominated by grassland and water body. It also revealed that LUCC magnitude in the watershed is low.

The article presents a study on the shift trend and step changes for runoff time series in the Shiyang River basin in northwest China. It states that seven statistical test approaches were used to determine the shift trends and step changes in the study. It discusses that Mann-Kendall test, Spearman's Rho test, linear regression and Hurst exponent were utilized to detect past and future shift trends for runoff time series, while the distributed-free CUSUM test, cumulative deviations and the Worsley likelihood ratio test were employed to detect step changes for the same time series. Results showed that the annual runoff from Zamu, Huangyang and Gulang rivers demonstrate statistically significant decreasing trends.

The article presents a study on the long-term monotonic trend and abrupt changes for major climate variables at 23 meteorological stations in the headwater catchment of the Yellow River basin in China from 1960 to 2001 on the basis of mean air temperature, precipitation, sunshine duration and pan evaporation. It states that the abrupt changes have been examined in terms of a five-year moving averaged annual series using the moving t-test (MTT) method, Yamamoto method and Mann-Kendall method. The results indicated that the annual air temperature has increased by 0.80 degrees Celsius in the headwater catchment of the Yellow River basin during the past 42 years.

The article analyzes the periodic properties of the annual runoff series for the last 40 years in Tarim River Basin in Xinjiang, China which were collected at hydrological gauging stations in its three main branches. It notes that analysis of variance and extrapolation method were employed to identify the annual runoff periods and predicted the future changes in the watershed using simulation methods. It also mentions that the Global Climate Model (GCM) has predicted the basin's long term trend of runoff because of the global increase in air temperature and precipitation in 1990.

The effects of land-use changes on the runoff process in the midstream plain of this arid inland river basin are a key factor in the rational allocation of water resources to the middle and lower reaches. The question is whether and by how much increasingly heavy land use impacts the hydrological processes in such an arid inland river basin. The catchment of the Heihe River, one of the largest inland rivers in the arid region of northwest China, was chosen to investigate the hydrological responses to hind-use change. Flow duration curves were used to detect trends and variations in runoff between the upper and lower reaches. Relationships among precipitation, upstream runoff, and hydrological variables were identified to distinguish the effects of climatic changes and upstream runoff changes on middle and downstream runoff processes. The quantitative relation between midstream cultivated land use and various parameters of downstream runoff processes were analysed using the four periods of land-use data since 1956. The Volterra numerical function relation of the hydrological non-linear system response was utilized to develop a multifactor hydrological response simulation model based on the three factors of precipitation, upstream runoff, and cultivated land area. The results showed that, since 1967, the medium- and high-coverage natural grassland area in the midstream region has decreased by 80.1%, and the downstream runoff has declined by 27.32% due to the continuous expansion of the cultivated land area. The contribution of cultivated land expansion to the impact on the annual total runoff is 14-31%, on the annual, spring and winter base flow it is 44-75%, and on spring and winter discharge it is 23-64%. Once the water conservation plan dominated by kind-use structural adjustments is implemented over the next 5 years, the mean annual discharge in the lower reach could increase by 8.98% and the spring discharge by 26.28%. This will significantly alleviate the imbalance between water supply and demand in both its quantity and temporal distribution in the middle and lower reaches. [ABSTRACT FROM AUTHOR]